Preparation And Application Explorations Of Freestanding Transparent Conductive Graphene Films

As early as 1986, the term "graphene" was proposed. But it was not until 2004,when Professor A. K. Geim stripped it from the high orientation of pyrolytic graphite for the first time, that a monatomic layer graphene of independent existence was obtained. Graphene, with its unique crystal structure, has exhibited many excellent properties on a wide scope that covers optics, mechanics, electrics, and thermo tics.Large-area graphene films have unique physical and chemical properties such as electron mobility, thermal conductivity, mechanical strength and the thickness of an atomic layer, which predicate itself a prosperous future in the optoelectronics field and the highly selective membrane separation field. However, what kind of assembly method should be applied to the fabrication of large-area, freestanding, transparaent and flexible grapheme films has become the problem that researchers needs to face and solve.Macroscopic assembly can create advanced materials with hierarchical structure and translate the property of individual building blocks into ensembles for specific application. Here we for the first time demonstrate the improved Langmuir-Blodgett(LB) macro assembly method fabricate of freestanding, highly transparent graphene oxide (GO) films under the synergy of unique wrinkled structure of GO nanosheets and strong interfacial interaction between GO and melamine, furthermore creating nacre-like graphene films with "brick & mortar" microstructure. The ultrathin,flexible GO film (?22 nm) consisting of two GO monolayers sandwiched with melamine delivers a large optical transmittance of 84.6 % at 550 nm and 90.7 % at 800 nm, and high mechanical strength of 45 MPa at a notable elongation of 3.5 %.The reduced GO film with resistance of 420 ??-1 exhibits excellent electromechnical stability with 10000 cycles at a small bend radius of 1.5 mm, presenting the potentials for flexible transparent conductors.Furthermore, also with the use of the explored improved Langmuir-Blodgett (LB)macro assembly method, and by means of the strong interfacial interaction between GO and polyacrylamide, the freestanding, highly transparent graphene oxide films are fabricated, which exhibit a superior mechanical strength and flexibility in the solution, in terms of a stress mechanical strength of 81 MPa at 12% strain under wet tensile test, as has fully demonstrated its application prospect in extreme environment.